Polynuclear complexes of a series of hydrazone and hydrazone–oxime ligands – M2 (Fe), M4 (Mn, Ni, Cu), and Mn (Cu) examples

Abstract

Tetranuclear, dinuclear and chain complexes involving some polyfunctional hydrazone and thio-carbohydrazone-based ligands are discussed. Ni(II) and Mn(II) [2×2] grids form with μ2-S and μ2-O bridges respectively, and are antiferromagnetically coupled (J=−167(5), −3.59(2) cm−1 respectively). With the Fe(II) based system oxidation to Fe(III) occurs, and a μ2-Ohydrazone bridged dimer results, with antiferromagnetic exchange between the S=5/2 spin centers (J=−22.5(2) cm−1). In the case of Cu(II) the diazine group acts as a μ2-N–N bridge between Cu(II) centers in two cases involving a tetranuclear and a chain complex. Non-orthogonal bridging through N–N and carboxylate bridges leads to antiferromagnetic exchange in the tetranuclear case (J=−32.7(7), −16.1(7) cm−1 respectively) and ferromagnetic exchange in the chain complex due to orthogonal N–N bridging (J=3.3(1) cm−1).